With the current popularity of portable communication devices and developed semiconductor fabrication technology, high speed and high performance transistors are more densely integrated on semiconductor dies. Consequently, the amount of heat generated by the semiconductor dies will increase significantly due to the large number of transistors integrated on the semiconductor dies, the large amount of power passing through the transistors, and the high operation speed of the transistors. Accordingly, it is desirable to package the semiconductor dies in a configuration for better heat dissipation.
Flip chip assembly technology is widely utilized in semiconductor packaging due to its preferable solder interconnection between flip chip dies and laminate, which eliminates the space needed for wire bonding and die surface area of a package and essentially reduces the overall size of the package. In addition, the elimination of wire connections and implementation of a shorter electrical path from the flip chip die to the laminate reduces undesired inductance and capacitance.
In flip chip assembly, mold compounds, formulated from epoxy resins containing silica particulates, are used to encapsulate and underfill flip chip dies to protect the dies against damage from the outside environment. Some of the mold compounds can be used as a barrier withstanding chemistries such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and acetylcholine (ACH) without breakdown; while some of the mold compounds having good thermal conductive features can be used for heat dissipation of dies.
To accommodate the increased heat generation of high performance dies and to utilize the advantages of flip chip assembly, it is therefore an object of the present disclosure to provide a method to package flip chip dies in a configuration for better heat dissipation. In addition, there is also a need to enhance the thermal performance of encapsulated flip chip dies without increasing the package size.